1. Field of the Invention
The present invention relates to a liquid crystal display apparatus and a cooling device, particularly, a liquid crystal display apparatus cooling a surface of a liquid crystal panel to which light is emitted from a light source and transmitting the light from the light source via a cooling fluid, and a cooling device for the same.
2. Description of the Related Art
There is known a liquid crystal display apparatus including a liquid crystal panel in which a liquid crystal layer is sealed between a pair of substrates. In the liquid crystal apparatus, the liquid crystal panel modulates the light emitted from a light source. And the apparatus displays an image by applying the modulating light. The above liquid crystal display apparatus has merits such as thin, light weight, and a lower power, compared with a cathode ray tube (CRT). Therefore, the liquid crystal display apparatus is applied as a direct view type display device to electric equipments such as a personal computer, a portable phone, and a digital camera, also, applied as a projection type display device such as a projector.
The liquid crystal display apparatus is demanded to display an image in a large screen in order to improve visibility.
In displaying the image in the large screen, a size of a display area of the liquid crystal panel is substantially equal to a screen size in the direct view type liquid crystal display apparatus. Therefore, the display area for the image is enlarged by adapting a large-sized liquid crystal panel or combining a plurality of small liquid crystal panels. Consequently, the direct type liquid crystal display device may be expensive in order to display the image in the large screen.
The projection type liquid crystal display apparatus emits light from the light source to the small liquid crystal panel, and enlarges and projects an image to be displayed on the liquid crystal panel through a lens to realize the resultant display of the image in the screen. Therefore, in this case, the projection type liquid crystal display apparatus can be produced in lower cost than the direct view type display device. Consequently, in displaying the image in the large screen, the projection type liquid crystal display apparatus has been used more than the direct view type display apparatus.
The projection type liquid crystal display apparatus, for example, is classified into a single-plate type and a three-plate type. The single-plate type divides the primary colors spatially or temporal by using a single liquid crystal panel, and displays an image. The three-plate type display apparatus displays the respective primary colors images on three liquid crystal panels, combines the images displayed on the three liquid crystal panels by a dichroic prism to form a single image, enlarges and projects the same, and displays the result on a screen.
When the above projection type liquid crystal display apparatus projects the image on the screen, most of the light emitted from the light source, not applied to the image projected and displayed on the screen, is absorbed into each of configuration members of the liquid crystal display apparatus such as the liquid crystal panel to generate heat thereof.
There is also known a liquid crystal panel in which a temperature range capable of realizing appropriate functions is limited. For example, when the temperature of the liquid crystal panel is higher than the rated temperature range, characteristics of a liquid crystal layer in the liquid crystal panel may change or air bubbles may be generated in the liquid crystal layer. And the displayed image quality may deteriorate. Otherwise, when the liquid crystal panel is retained for a long time at the temperature other than the rated temperature, the performance thereof may deteriorate, and a lifetime of the apparatus may be shortened. Therefore, the projection type liquid crystal display apparatus in which large intensity light is emitted to the liquid crystal panel is provided with a cooling device for cooling the liquid crystal panel.
In order to cool the liquid crystal panel, as a cooling device, Japanese Unexamined Patent Publication (Kokai) No. 2003-302619 discloses an air cooling system, and Japanese Unexamined Patent Publication (Kokai) No. 05-264947 discloses a fluid cooling system.